package p2000;

import java.util.Scanner;

public class Main2071MaxNum {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int t = scanner.nextInt();
        while (t-- > 0) {
            int n = scanner.nextInt();
            Float r = 0.0F;
            while (n-- > 0) {
                Float a = scanner.nextFloat();
                if (r.compareTo(a) < 0) {
                    r = a;
                }
            }

            System.out.println(String.format("%.2f", r));
        }
    }

}
